Help with Cable Modem- TROUBLESHOOTING.

Quote from menace33 : For short range, yes. Also far less interference than the 2.4 GHz range, however, 5 GHz is really only as good as what separates you and your router. I personally haven't jumped on the 5 GHz bandwagon, but I see its usefulness.

Thank you SIR!

Quote from menace33 : I'm a huge fan of the Motorola Surfboard cable modems and the SB6121 is no different in feeling.

So now I've got a new problem. I've updated the OP. I'd appreciate any advice.

HELP!!

what's the signal strengh? 192.168.100.1

what's the modem logs say.

did you remember the time it loss signal? exact time everynight?

Quote from Airi : what's the signal strengh? 192.168.100.1 what's the modem logs say. did you remember the time it loss signal? exact time everynight?

I've uploaded 2 screen shots. Is that what you're talking about?


The logs just has a whole bunch of cryptic stuff that I don't understand. But it mentions my MAC address a whole bunch of times, so I don't want to post that information here.

Alright so your SNR is wonderful. It should be between 30 and 40 dB.
Your downstream power levels are pristine at 0 dBmV. That means that Comcast is not struggling to send a signal to your modem.
Your upstream power levels are ok and could be better. This means that your modem has to consume more power to send a signal back to Comcast for proper sync with the head end.

My upstream power level for my SB5101 stays at 52 dBmV and I never have a signal drop that is not pre-planned by Comcast.

By the read of it, everything is normal enough to where they aren't overly concerned about it nor would I if I saw these numbers.

Quote from menace33 : Alright so your SNR is wonderful. It should be between 30 and 40 dB. Your downstream power levels are pristine at 0 dBmV. That means that Comcast is not struggling to send a signal to your modem. Your upstream power levels are ok and could be better. This means that your modem has to consume more power to send a signal back to Comcast for proper sync with the head end. My upstream power level for my SB5101 stays at 52 dBmV and I never have a signal drop that is not pre-planned by Comcast. By the read of it, everything is normal enough to where they aren't overly concerned about it nor would I if I saw these numbers.

My Upstream stays at a steady 49 dBmV. And everytime the modem reset/restarted, I've seen those numbers jump to 51-52. Now the Motorola techie says that , that increase is causing the refresh (though I obviously don't know the dynamics of why it's happening). But he assured me that this is Comcast's fault and not the fault of the modem.

Obviously it can't just be a coincidence, can it? A Comcast technician is going to come over tomorrow. if not the upstream power levels, what else could be causing this?

Quote from the.J129 : Obviously it can't just be a coincidence, can it? A Comcast technician is going to come over tomorrow. if not the upstream power levels, what else could be causing this?

Honestly there is no way to prove Motorola right or Comcast wrong. Comcast downstream levels to the modem are on point so no complaints there. However, these blips that reset the modem are so short that you could check the modem logs to see if there are any specific messages that correspond to that exact moment of the blip and are consistent. However, you'd need to know some Comcast tech that would know how to interpret those. You could ask Motorola to help interpret them. Maybe they could, maybe not.

It could be a reset signal that's getting sent to the modem but there are all sorts of other asinine possibilities like your neighbors poorly shielded microwave from the 70's is turned on, the wind gusts, somebody's sprinklers switch on a water gets where it doesn't belong, the rats in you wall bump the cable they partially gnawed through,... the list is endless but DSL is more prone to problems of this nature than cable. When you have problems like this weather and construction projects in your area are always things to think about.

It could also be related to fluctuations in the AC line voltage in your dwelling. This is fairly unlikely but you could always try a UPS with AVR. The point is think about as many of these things as you can and see if there's any correlation.

It's pretty typical for there to be a little downtime, I've typically had cable go down for 30-60 minuets about once a month usually around 3am. It these resets aren't happening more than a couple times a day and your internet comes right back up, it's hard to complain too much.

Quote from jkee : It could be a reset signal that's getting sent to the modem but there are all sorts of other asinine possibilities like your neighbors poorly shielded microwave from the 70's is turned on, the wind gusts, somebody's sprinklers switch on a water gets where it doesn't belong, the rats in you wall bump the cable they partially gnawed through,... the list is endless but DSL is more prone to problems of this nature than cable. When you have problems like this weather and construction projects in your area are always things to think about. It could also be related to fluctuations in the AC line voltage in your dwelling. This is fairly unlikely but you could always try a UPS with AVR. The point is think about as many of these things as you can and see if there's any correlation. It's pretty typical for there to be a little downtime, I've typically had cable go down for 30-60 minuets about once a month usually around 3am. It these resets aren't happening more than a couple times a day and your internet comes right back up, it's hard to complain too much.

Well, I've had DSL for about 4.5 years before this...and in all that time, the ONLY time the internet stopped working was ONCE when the modem died...and ATT had to send me a new dsl modem... So you can see, how, having dumped ATT for Comcast, having the internet disconnect 4-5 times a day can be frustrating. Heck, the DSL line is hanging outside my window, and it has weathered snowstorms, heavy rain and NEVER failed.


Also- all the reasons that you mentioned apparently happen more often with DSL than with cable modems? Then they surely can't be the reason here, because I've never had any problem with my DSL modem.

Okay so the technician came...did some rewiring outside the house and climbed up the pole to check things out... Every thing looked fine...

And then the resetting began again. So, he said, maybe it's a problem with the modem? Heck, who knows... So I got the same modem from Amazon, and activated it. It worked fine until it reset itself 5 times within half an hour day before yesterday (when it began raining...), and it reset itself twice yesterday. The tech is going to come over again on monday.


Do you guys think it could just be a batch of bad modems? I can always switch to something else...like this [amazon.com].
When the modem works, it works beautifully.


So now what? This is really frustrating.

I had the exact problem a few months ago. Internet kept resetting itself totally randomly. Called optimum many many times. Technicians came over a few times, replace the modern, rewire the cable. Finally they replaced it with a DOCSIS 3.0 modern and that solved the problem, but since you have already bought a DOCSIS 3.0 modern, it could be a different issue...

FYI I had random problems losing Internet.but not LAN. I found a setting to reboot my modem weekly in. The early morning. Now I don't have issues

Sadly, the SB6121 does not have a reboot modem where you can set it to do it weekly. You can do it manually but not task it to do it weekly.